This is the 677th most frequent Russian word.
установить
To install, establish, set, or determine.
The word 'установить' is used here to mean 'install', commonly referring to setting up equipment.
Мы решили установить новый кондиционер в гостиной.
We decided to install a new air conditioner in the living room.
In this context, 'установить' means 'determine', used figuratively to designate finding or defining something.
Учёные смогли установить причину этого явления.
Scientists were able to determine the cause of this phenomenon.
Here, 'установить' is employed to signify 'establish', indicating the act of confirming or asserting facts.